Reading through the K341 manual I noticed it says API Service Class SF or SG. The Castrol SAE 30 I picked up the other day is API SM, the latest. Has anyone found these new oils to mess with the old engine designs. I don't even know if the old K series motors are flat tappet, but some say the reduction of ZDDP in the SM stuff hinders flat tappet motors. What's your opinion?